Among various types of flat panels, organic light-emitting diode (OLED) displays have outstanding properties, including being light weight, thin, self-illuminating, having a short response time, wide viewing angles, a wide color gamut, high brightness, and low power consumption. Thus, OLED displays have gradually become a mainstream, next generation display technology. In comparing OLED displays with LCDs, OLED displays save more energy, are thinner, and have wider viewing angles, which the LCDs cannot achieve. Nevertheless, users are getting increasingly unsatisfied with the resolution of displayed images, and production of OLED displays with high quality and high resolution still faces a lot of challenges.
Current touch control technology can be generally classified to include an out-cell touch control technology and an in-cell touch control technology. The in-cell touch control technology is characterized by integrating touch sensors inside the display panels. Because the in-cell touch control technology, compared to the out-cell touch control technology, enables display apparatuses to have relatively lighter weight and be thinner, manufacturers of the OLED display apparatuses are directing their attention toward in-cell touch control technology. In contrast, the out-cell touch control technology is characterized by embedding a touch control screen between a color filter substrate and a polarizer of the display screen (i.e., disposing the touch sensors on the liquid crystal display panels), and thus the out-cell touch control technology, when compared to the in-cell touch control technology, would be a better choice to more easily manufacture the display apparatuses.
With the development of flexible display screens used in OLED displays, the touch control screens are being combined with the flexible display screens to be flexible and pliable as well. However, conventional touch control screens manufactured, based on a transparent conductive film, cannot meet desired flexibility requirements. On one other hand, because the conventional touch control screens have to be first manufactured independently, and then adhered to upper surfaces of the OLED screens via an optical transparent adhesive to form a complete touch control display module, such technology requires an additional bonding step and increases the entire thickness of the module. This is not helpful in enabling flexible touch control display screens being light weight and thin.
In the method for manufacturing conventional touch control display screens used in OLED displays, the touch control sensors are generally formed on OLED encapsulation film. For example, the flexible touch control sensing metal grids are formed by executing steps such as deposition, exposure, development, etching, stripping, and rinsing during the process. For the etching step, the touch control sensing electrodes and the metal binding area are etched to reach different etched depths. In the prior art, two masks are independently used to separately perform an etching step for formation of the through-holes at two ends of the metal bridge and another etching step for formation of the through-holes in the metal binding area, so as to form the two through-holes having different depths. This conventional method, though avoiding interference between formation of the through-holes during the etching step thereof, an additional mask is required. This not only increases manufacturing cost but lowers manufacturing efficiency.